Intestinal Inflammation: Signaling proteins and the rate of PMN transmigration

描述(申请人提供)：胃肠粘膜中性粒细胞(PMN)迁移是宿主防御和炎症性肠病(IBD)等病理生理过程的中心组成部分。虽然许多研究集中于在细胞黏附水平上定义参与调节PMN迁移的事件，但对于在炎症反应过程中用于调节PMN通过肠粘膜的迁移速率的事件却知之甚少。我们课题组的研究已经证明了上皮和PMN表达的膜蛋白的重要贡献，这些蛋白在连接时启动信号，对PMN迁移的动力学有深刻的影响。这项建议将集中在一对称为CD47-SIRPalpha的受体-配体对和一类称为蛋白酶激活受体(PARs)的蛋白质上，这些蛋白质在肠粘膜和白细胞上差异表达，并通过对PMN和上皮细胞的不同作用来调节PMN的迁移速度。我们观察到，迁移性PMN暴露于肠道来源的微生物产品对移行有深远的影响，这可能部分与CD47介导的信号转导有关，部分可能与PMN通过PARs刺激的上皮通透性改变有关。我们的总体目标是了解CD47、SIRP和PARS如何在结构和功能的基础上调节PMN在肠道中的迁移。为了实现这一目标，我们将结合急性结肠炎小鼠模型进行体外研究，以确定肠上皮细胞和表达CD47的中性粒细胞对中性粒细胞跨上皮迁移速率的贡献(S)，确定SIRPalpha中介导配体结合/蛋白质相互作用的结构元素，并探讨通过PARS调节中性粒细胞跨肠上皮迁移速率的作用。了解调节中性粒细胞跨上皮迁移速度的基本机制可能会为粘膜的病理生理学提供线索！例如IBD等疾病，并有助于开发新的治疗策略，旨在减少与这些疾病相关的渗透性增强和粘膜损伤。

DESCRIPTION (provided by applicant): Neutrophil (PMN) migration in the gastrointestinal mucosa is a central component of both host defense and pathophysiologic processes such as inflammatory bowel disease (IBD). While many studies have focused on defining events involved in the regulation of PMN migration at the level of cell adhesion, events that serve to regulate the rate with which PMN migrate through intestinal mucosa during the inflammatory response are poorly understood. Studies from our group have demonstrated important contributions from epithelial and PMN expressed membrane proteins which, upon ligation, initiate signals that have profound effects on the kinetics on PMN transmigration. This proposal will focus on a receptor-ligand pair termed CD47-SIRPalpha and a class of proteins termed protease activated receptors (PARs) that are differentially expressed in the intestinal mucosa and on leukocytes and modulate the rate of PMN transmigration through distinct effects on PMN and epithelial cells. We have observed that exposure of migrating PMN to gut-derived microbial products have profound effects on transmigration that may be linked in part to CD47 mediated signaling and in part to PMN stimulated alterations in epithelial permeability through PARs. Our overall goal is to understand the mechanisms of how CD47, SIRP and PARs regulate PMN transmigration in the gut on a structural and functional basis. To achieve this goal we will perform studies employing in vitro methods in concert with murine models of acute colitis to define the contribution(s) of intestinal epithelial and PMN expressed CD47 and potential crosstalk with TLRs on the rate of PMN transepithelial migration, determine structural elements in SIRPalpha that mediate ligand binding/ protein interactions and investigate the role of PMN-epithelial signaling through PARs in regulating the rate of PMN migration across intestinal epithelium. Understanding basic mechanisms regulating the rate of PMN migration across epithelia may provide clues to the pathophysiology of mucosa! diseases such as IBD and aid in the development of new therapeutic strategies aimed at diminishing enhanced permeability and mucosal injury associated with these conditions.